Every DMA can only measure in a limited stiffness range. Even if you select the best possible sample geometry, sometimes you have a soft or liquid-like sample or a very stiff sample. In these cases you must apply either a very small or a very high force.
The available force range is: 0.001 to 40 N
Depending on the measurement mode, part of the force is used for stretching the sample. This is the case for tension, compression and 3-point-bending. The dynamic force amplitude for these deformation modes is smaller than the static, so called offset force.
The larger the force range the more experimental flexibility you get.
In this example the linear range of the sample is measured.
The DMA modes can only be used in the linear range of the stress-strain curve.
This measurement starts in the glassy state of the sample when it is very stiff.
On heating, the shock cooled material exhibits a glass transition at -115 °C, crystallization at -100 °C and melting at -40 °C. Afterward it is liquid (G’’ > G’). At 120 °C, the phase angle almost reaches the limit of π/2 radians for a Newtonian fluid (very low stiffness).